25 ℃、101 kPa下，1 g氢气完全燃烧生成液态水时放出热量142.9 kJ，则下列热化学方程式书写正确的是

A．2H2O(l) ===2H2(g)＋O2(g)；ΔH ＝+571.6 kJ·mol^－1

B．2H2(g)＋O2(g)===2H2O(g)；ΔH ＝－571.6 kJ·mol^－1

C．2H2(g)＋O2(g)===2H2O(l)；ΔH ＝+571.6 kJ·mol^－1

D．2H2(g)＋O2(g)===2H2O(l)；ΔH ＝－285.8kJ·mol^－1